We have several dozen SQL Servers, with multiple databases per server, that
are backed up nightly using NetBackup 6.0 MP4. Periodically, we will have
individual database backups fail with a status 42. The detailed status for
the job will show the following:

All other databases on the server will back up successfully. If we rerun
the backups, the 'failed' database will generally back up without issue.

We see this error probably 5 times a week. It appears on several different
server, with several different databases, and there does not seem to be any
discernible pattern. There are no network errors in the Windows system logs.
In fact, if we look at the SQL Server logs, they will show that the backup
completed successfully: